Mechanism and kinetics of the shock‐tube decomposition of vinylsilane

Abstract

The shock-induced thermal decompositions of vinylsilane and vinylsilane-d, (0.2% on argon) have been studied in the temperature range of 1085-1275 K, and at total pressures of about 3100 tom. In systems without silylene traps, some induced decomposition occurs which is attributed to the silylene chain sequence VSiH + C,H, + SiH,, SiH2 + VSiH, VSiH,SiH, + VSiH,SiH + Hz, VSiH,SiH + VSiH + SiH2. In the presence of silylene traps (butadiene and acetylene), the overall decomposition kinetics are log HVSiH,, s-'1 = 14.95 -63,268 ca1/2.303RT and log MVSiD,, s-l) = 15.14 -64,815 ca1/2.303RT. Three primary processes contribute to the decomposition: l,l-H, elimination, 1,2-H2 elimination, and ethylene elimination. Two mechanisms are proposed, one for exclusive primary process formation of C2H4, and the other for both primary and secondary formation routes. Modeling studies are reported which show that both mechanisms can be made compatible with the rate and product yield data within experimental errors.

UV Laser Photodeposition of Nanotextured Poly(hydridomethylsiloxane) Powder from Gaseous 1,3-Dimethyldisiloxane

“…4 ] extrusions, and homolysis of the Si±C, Si±H, and Si±O bonds can be expected to occur. [16,17] Since the Si±O bond split is an unlikely primary photochemical event, [18] this gives support to the concept of secondary reactions in which DMDSO undergoes radical attacks that produce reactive intermediate(s) in which cleavage of the Si±O bond is more feasible. We presume that silicon-centered radicals (produced upon the photolysis of DMDSO at the Si±H or Si±C bond) undergo cleavage into the silanone and the smaller Si-centered radical (Eqs.…”

Secondary dissociation pathways of ethylsilylene radical on ground and excited state potential energy surfaces

“…Consequently, the energy of activation for reaction (3) is given by the enthalpy of reaction. Its energy of activation is 115.9 kJ mol J. Rickborn et al [6] estimated an upper limit for the activation energy as 128-8 + 17 kJ mol-~ from shock tube studies on ethylsilane. The result from this study is consistent with their experimental estimate.…”

“…One of the simplest alkysilanes is ethylsilane. Silylene has been suggested to result from primary dissociation pathways of ethylsilane through a 1,2-SiH2 elimination process [5,6,12], viz., CH3CHESiH 3 --~ CEH 6 + Sill 2.…”

“…The key intermediate implicated in the formation of amorphous silicon thin films is the silylene (Sill2) radical [1][2][3][4][5][6]. Consequently, improving deposition rates of organosilanes entails identifying chemical sources of Sill2 from the decomposition process, so yields of the intermediate can be enhanced.…”

Silylenes

“…Three-membered rings were obtained from 34 and unsaturated hydrocarbons, and trapping of 34 with sulfur and selenium led to interesting cyclic products. The most surprising reactions of 34 are those with naphthalene and benzene, illustrated in equation 70 In a very recent report, Okazaki and coworkers describe the reaction of 34 with hindered isocyanides 35a c, leading to the first examples of stable silylene Lewis base complexes 36a c (equation 78) 145 . The latter were isolated as blue-green to blue solids, stable up to 60°C.…”